The corrosion behaviour of a TiAl coating exposed to a simulated dry-feed entrained slagging coal gasifier atmosphere containing 0.8% H2S at 600 degrees C

Two steel samples coated with TiAl were exposed at 600 degrees C to a CO-ba sed reducing gas mixture containing 0.8% H2S for periods of up to 1000 h. M ass changes were recorded every 250 h and surface XRD and SEM studies carri ed out after 500 h. A full surface and cross-sectional microscopic examinat ion was also carried out at the termination of the experiment. The study showed that a radical improvement in resistance to sulphidation a ttack was associated with the presence of the TiAl coating, in sharp contra st to the severe corrosion noted on noncoated regions of the samples where a thick FeS had formed. The commercial potential for applying this type of coating to components seeing service in highly reducing, sulphur-containing process gases is discussed.